This is an open-label, international, multicenter continuation study in subjects who have participated in a previous 534U87 study. The primary objective of this trial is to evaluate the long-term safety and tolerability of open-label 534U87 in subjects with epilepsy. The secondary objectives are to evaluate long-term efficacy of open-label 534U87 in subjects with epilepsy and to assess the over all change in health-related quality of life (HRQoL) and seizure severity. The study will consist of a screen visit followed by the Treatment Phase.